The present invention generally relates to laser-diode pumped solid-state laser apparatuses, optical scanning apparatuses, image forming apparatuses and display apparatuses. More particularly, the present invention relates to a laser-diode pumped solid-state laser apparatus having a solid-state laser crystal in which pumping is caused by laser diode. Further, the present invention relates to any of an optical scanning apparatus, an image forming apparatus or a display apparatus that uses such a laser-diode pumped solid-state laser apparatus.
These days, lasers are used in various fields including laser printers and laser measuring instruments. Further, aiming practical application in future, investigation and development are being made with regard to laser display apparatus or the like. In such apparatuses that use laser light, there is an increasing demand for downsizing of laser source and improvement of laser light quality.
Various proposals have been made with regard to so-called solid-state lasers (see Patent References 1-11, for example).
For example, Patent Reference 1 discloses a solid-state laser oscillation apparatus that uses a laser medium having a doped part and undoped part. Further, Patent Reference 2 discloses a laser apparatus having a gain medium and a waveguide of pumping light, while Patent Reference 3 discloses a laser apparatus having a laser medium and a waveguide optical system.
Further, Patent Reference 4 discloses a method of manufacturing an oxide monocrystal (single crystal) having a core part and a cladding part, while Patent Reference 5 discloses an oxide monocrystal of fiber shape for optical applications formed of a fiber body of an oxide monocrystal and a liquid-phase epitaxial layer of an oxide monocrystal formed so as to cover the surface of the foregoing fiber body. Further, Patent Reference 6 discloses a solid-state laser crystal in which doping concentration of laser-activating ions is increased continuously or stepwise from an end surface where excitation is caused toward an end surface where cooling is made.
Further, Patent Reference 7 discloses a composite laser device having a transparent crystal body including therein a region where laser oscillation can take place and a second crystal body jointed to the transparent crystal body, wherein at least one of the transparent crystal body and the second crystal body is formed of a polycrystalline material. Further, Patent Reference 8 discloses a solid-state laser oscillator having a polycrystalline ceramic composite laser medium in which a polycrystalline transparent ceramic not containing active element and a polycrystalline transparent ceramic doped with an active element are jointed.
Further, Parent References 11 and Non-Patent Reference 1 disclose a composite monocrystal that has regions formed by so-called dual-die EFG (edge-defined film-fed growth) process with different compositions or components.
Patent Reference 1
Japanese Patent 3,503,588
Patent Reference 2
Japanese Laid-Open Patent Application 2004-356479
Patent Reference 3
Japanese Laid-Open Patent Application 2004-152817
Patent Reference 4
Japanese Patent 3759807
Patent Reference 5
Japanese Laid-Open Patent Application 8-278419
Patent Reference 6
Japanese Patent 3266071
Patent Reference 7
Japanese Laid-Open Patent Application 2005-327997
Patent Reference 8
Japanese Laid-Open Patent Application 2002-57388
Patent Reference 9
Japanese Laid-Open Patent Application 6-128089
Patent Reference 10
Japanese Laid-Open Patent Application 6-128076
Patent Reference 11
Japanese Laid-Open Patent Application 6-128078
Non-Patent Reference
P. Rudolph, K. Shimamura and T. Fukuda, “The Radial Selectivity of In-situ Core-doped Crystal Rods Grown by the Double Die EFG Method, Cryst. Res. Technol. vol. 29, 1994, No. 6, pp. 801-807.